Generally, in cutting, a cutting fluid is used for discharging chips generated in the cutting. For example, Japanese Patent Application Laid-Open Publication No. H11-333630 discloses a tap having, inside its body, an oil hole through which the cutting fluid flows, and a branch hole communicating with the oil hole. A top portion of the branch hole is open inside a chip discharging groove.
In this tap, the cutting fluid which has flown through the oil hole is delivered from the branch hole to the chip discharge groove, and discharged along the chip discharge groove. Accordingly, the chips can be discharged from the chip discharge groove together with the cutting fluid.
As a tap in which chips can be discharged without using the cutting fluid, a deep hole tap having a vertical hole inside its body and a lateral hole communicating with the vertical hole is known. A top portion of the lateral hole is open to an outer peripheral surface of the body.
In this deep hole tap, the chips which have entered the vertical hole are gradually pushed up by newly generated chips, and the body rotates, so that the chips which have flown through the vertical hole can be discharged from the lateral hole.